Thus, for example, TTS with the active ingredients buprenorphine and fentanyl are the pharmaceutical forms of choice for the treatment of chronic pain in long-term therapy. The continuous delivery of these highly effective analgesics through the skin provides a continuous supply of analgesic to a patient with pain, so that plasma peaks and plasma troughs are avoided.
This has the advantage that both side effects due to overdoses, but also states of pain due to undersupply, are avoided by a low but sufficient plasma concentration of the active ingredient. The skilled worker knows for example of the commercial products TRANSTEC®, but also DUROGESIC® or DUROGESIC® SMAT, which have proved useful in pain therapy for some time. The disadvantage of TTS in pain therapy is that to maintain the so-called concentration gradient and thus the desired plasma level of the active ingredient during the period when the TTS is applied, it is always necessary for more active ingredient to be present in the TTS than is actually delivered to the patient. This results in worn TTS representing a potential for abuse by, for example, members of the drug scene, because these groups of people are perfectly capable of collecting used TTS and extracting them with the most primitive means in order to obtain the active ingredient still present therein and misuse it for appeasing the drug addiction.
There has in the past therefore been no lack of attempts to suppress this misuse by advising patients to cut up the worn patch and put it down the toilet to reach the sewerage system. The disadvantage of this method is that neither the legislature nor the pharmaceutical manufacturer can guarantee that this procedure is in fact followed by patients. For this reason, TTS which contained an antagonist, besides the active ingredient, have been developed (e.g. WO 2004/098576, WO 90/04965, WO 2004/037259). The intention thereby was to prevent or at least markedly impede the obtaining or extraction, described above, of the analgesic active ingredient from used TTS. These protective measures have, however, not proved adequate for preventing medicament abuse because it is still possible with relatively simple means to separate the actual active ingredient from the antagonist by fractional precipitation.
WO 02/094172 describes a system for preventing misuse of dosage systems, but the active ingredient in this system still remains activatable and is not destroyed. Likewise in WO 2005/070003; the active ingredient therein is merely absorbed, which still makes the possibility of separation from the ab/adsorbent possible. Finally, WO 2004/098568 describes an “abuse-resistant” transdermal dosage system. Just like the other known systems of this type, once again the active ingredient is not destroyed but is merely neutralized in effect by an antagonist.